January 17th, 2022 by Sarah Miles

Weight loss is a multi-million-pound industry and while strategies can range from food restriction diets, weight loss clubs, exercise regimes, and even pills and surgery, there is one very simple thing that you can do to improve your chances of successfully losing weight this year and that is to improve the quality and duration of sleep.

But how does sleep relate to weight? While it’s not as obvious as eating too much or not doing enough exercise, poor sleep has a direct negative impact on weight for a number of reasons. We have broken them down into four main areas: energy, physiology, brain, and cycles of behaviour:

Energy

Sleep helps your body rest and recover and therefore gives you energy. If it doesn’t have the opportunity to do this properly, you will feel tired and lack energy. This results in:

Reaching for high energy foods and drinks

This might be getting a latte on your way into work or choosing foods that are high in sugar or caffeine such as cakes, sweets, or chocolate. If you’re tired, a quick hit of comfort food will always seem more appealing than anything else, and it can be hard to resist.

Being too tired to shop for and cook healthy foods

This means you might be more likely to opt for takeaways or calorie-loaded ready meals, so you can spend less time cooking and more time resting.

Skipping exercise

Nobody wants to go to the gym or go for a run if they’re tired. Skipping physical activity makes it hard to burn off calories consumed, and it can lead to a vicious cycle of tiredness and weight gain.

Physiology

Sleep deprivation affects how our body works in various ways that can influence how much we eat and how our bodies process that food:

Hunger hormones

Our bodies are designed to signal when they are hungry or full so that we know when and how much to eat. The feelings of hunger or fullness are triggered by the release of hormones ghrelin and leptin, respectively. When we are sleep deprived, we release more ghrelin and less leptin, making us much more likely to overeat.

Nervous system

Lack of sleep can influence the sympathetic nervous system and increase cortisol levels, which is a hormone related to stress. Increased feelings of stress can not only cause us to eat more but further prevent us from sleeping

Metabolism

Not getting enough sleep can reduce your resting metabolic rate (RMR), meaning that your ability to burn calories is compromised. Fat oxidation, the process of breaking down fat, is also suppressed

Brain

Lack of sleep affects brain function, and this can make us eat more for a couple of reasons:

Reward centre

The reward centre of our brains, the part that seeks out satisfaction, is stimulated more by high-calorie comfort foods when we are tired. This means we are far more likely to crave the bowl of ice cream than the fruit salad.

Frontal lobe

Poor sleep dulls activity in the frontal lobe of our brains, which is responsible for decision making and impulse control. This means we often don’t have the mental clarity needed to make good decisions about food.

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Cycles of behaviour

The relationship between sleep and eating has the potential to be a self-supporting one or a destructive cycle:

Late-night snacking

Staying up late not only limits the amount of sleep we get but also increases the likelihood of late-night snacking as there is a longer period between eating an evening meal and going to bed. Eating before going to bed can affect the quality of sleep we then get as it’s harder to settle and can cause conditions such as acid reflux or indigestion. Poor sleep causes poor eating causes poor sleep and so it continues.

Energy and exercise

Getting enough sleep allows our bodies to rest properly and recover. We then wake up with plenty of energy for the next day. Just as lack of energy stops us from exercising, having plenty of it allows us to undertake physical activity, whether that be a formal exercise regime or just walking the dog or tackling the housework with enthusiasm. This in turn tires us out by the evening, making it easier to sleep thereby creating a positive pattern of behaviour.

Sources:

https://www.healthline.com/nutrition/sleep-and-weight-loss#TOC_TITLE_HDR_8

https://www.webmd.com/diet/sleep-and-weight-loss#1